1. Field of the Invention
The present invention relates to the sealing of tubing. In particular, but not exclusively, the present invention relates to the sealing of a joint between expandable tubing sections.
2. Description of the Related Art
In the oil and gas exploration and production industry, expandable tubing has been developed and has a variety of uses. These include expandable borehole casing and liner, and expandable sand exclusion based tubing assemblies, such as those disclosed in International patent publication no WO97/17524 (Shell), and as sold under the ESS Trademark by the present applicant.
Expandable tubing offers a number of advantages over conventional borehole tubing, as the expandable tubing can be run into a borehole in an unexpanded state and subsequently expanded downhole. This allows the tubing to be run through existing tubing and then expanded to a larger diameter within the borehole.
The expandable tubing sections typically include a male threaded portion (pin) and a female threaded portion (box) at opposite ends, for joining adjacent sections of tubing together end to end. Maintaining a seal between the pin and box portions post expansion can be problematic.
The sealing of sections of conventional, non-expandable tubing can also be problematic and can involve complex sealing systems.
It is amongst the objects of embodiments of the present invention to obviate or mitigate at least one of the foregoing disadvantages.